This invention relates to improved liquid crystal cells and particularly, to a process for sealing the liquid crystal cell after pouring of a liquid crystal material.
The liquid crystal material changes its optical properties in response to an applied electric field, magnetic field or heat. Employing these phenomena, the liquid crystal material are used in the form of a thin layer cell for display of numerical figures, characters and other symbols or patterns, detection of beams, modulation of optical systems, observation of mode patterns, non destructive inspection, and light valves for diaphram of cameras and contrast modulation of cameras, and materials for decoration.
The liquid crystal cell includes two planar supports with a thin liquid crystal layer between them, said supports being fixed at intervals of a limit by a spacer. The supports are usually of glass plate and coated with conducting layers for application of an electric field, resistor layers for heat impressing, radiation heat convertible material layers and light absorptive or reflective layers. The spacer provided between two planar supports only on the margin secures them at intervals of a limit with use of one having adhesive property in itself or an adhesive to form a cell structure having an aperture. The cell has at least one opening through which the liquid crystal material is poured into the aperture. The openings are sealed with adhesives. For this purpose epoxy-type adhesives which are of two-part is used in general. However, when the epoxy-type adhesive of which the cure reaction is too rapid is used, it is difficult to obtain liquid crystal cells having quality uniformly controlled because the assembly of the liquid crystal cell is restricted by time. For this reason, the epoxy-type adhesive having a moderate cure reaction is normally used, but it takes considerable time to completely cure the resin. During the cure reaction, curing agents such as amino compounds or polyamides are incorporated or effused into the liquid crystal layer and therefore, reduction of the mesomorphic range, increase of the current density and reduction of the life occur to the liquid crystal element so that the cells having uniform quality can not be obtained. Further, the curing agent must be added in an exact amount, otherwise the three-dimensional cure reaction does not sufficiently proceed so that sealing effects cannot be obtained with certainty and thus, the sealed parts are reduced in mechanical properties and liable to be peeled off. Moreover, since it is necessary to fix the assembled element during drying of the adhesive, operation efficiency is reduced.